Difference between revisions of "Programmer's Guide"

Revision as of 15:31, 11 August 2007

Introduction to the LinuxMCE Architecure

Our distribution includes hundreds of scripts and utilities that LinuxMCE has written to fully automate everything so that a PC with LinuxMCE becomes a 'turn it on and press play' appliance, rather than a traditional software application. However if you strip away all this stuff, the guts of LinuxMCE is software written in cross-platform c++. In fact nearly all LinuxMCE's code runs on Windows too.

This guide explains the architecture of the main C++ code. Documentation for all the scripts and utilities that make up the distribution is here.

LinuxMCE uses an extremely modular architecture. The heart of LinuxMCE, the 'main application' DCERouter is nothing but a general-purpose message router. It has absolutely no code relating to any of LinuxMCE's functionality--it just relays messages between devices. The functionality of LinuxMCE is, therefore, entirely in separate modules (ie Devices) which all run independently and communicate with each other by passing messages through DCERouter over sockets. There can be hundreds of these devices in a smart home, that do all sorts of things. As shown in the diagram below, many of LinuxMCE's devices are actually 'wrappers' we have written for existing open source projects that allow them to work together seamlessly in a LinuxMCE system. For example, we wrote a wrapper for Asterisk that sends event messages to DCERouter whenever a phone call comes in, and receives command messages when it is time to place a call. How the wrapper communicates with the open source project depends on that project. Our Asterisk wrapper, for example, communicates with Asterisk over a socket. It is really a translator converting messages from its socket connection with DCERouter into messages from its socket connection with Asterisk. The wrapper for the Xine media player links in Xine's own library and calls Xine functions directly.

<img src="include/images/quickstart/swmodules.jpg" border="0">

Since there are literally thousands of home automation components and pieces of a/v equipment that require controlling with RS232, USB and Ethernet we developed a special system for these devices using GSD. It's fast and often doesn't require any real programming skills. It can be used to support lighting control systems, climate and pool systems, external devices like i/r emitters, cameras, etc. If that's your interest skip this whole page and What if you don't have a driver for my home automation device Otherwise if you're a "real" programmer interested in adding new software modules or adding wrappers for existing software, then continue with this section.

Programmer's Guide Sections

• Why should I use the LinuxMCE platform for my project?
  • Overview of the software modules
  • A new concept in collaborative development
  • Adding support for home automation devices
• STEngine
  • OpenGL implementation
  • Photo Screen Saver
• ZWave implementation
• AVWizard specifications
• Orbiter
• wxWidgets
• Window manager
• Window controller
• X11 locking
• X11 pointer shapes
• LinuxMCE Plugins
• I want my software to run on LinuxMCE but it isn't open source
• Will you host, compile and support the LinuxMCE plug-ins for my
• GSD - Ruby codes
  • Apex Destiny 6100 (alarm panel)
• Automated_Builder

Is LinuxMCE a stand-alone software product, or a development platform?

LinuxMCE is sold commercially as a complete turnkey appliance. To the end user it appears to be 1 single application with 1 common user interface. From a developer's standpoint, however, LinuxMCE is actually a platform for developing smart home modules that all work together. Much of the top-level functionality is provided by a variety of open source projects. LinuxMCE adds it's own home automation engine, UI front-end, configuration web site, and the heart of it all, LinuxMCE Libraries DCE, which allows this collection of devices and software projects to work together as a seamless whole.

In many cases, a LinuxMCE DCE device is just a thin wrapper for another open source project. The wrapper's job is to launch the open source project with the right parameters, forward incoming commands to it, and fire DCE events in response to triggers within it. We added DCE wrappers for the projects Asterisk (pbx telephone switch), Linphone (SIP software telephone) and Motion (surveillance video capture). In most cases, no modifications to the open source project were needed since the project already contained a mechanism for feeding it commands.

The software is completely modular and we offer a wealth of development tools, like code generators, design tools, a rapid development module for adding new devices (GSD), our own messenging platform and a ton of general-purpose libraries. Our GSD+sqlCVS is an entirely A new concept in collaborative development for quickly adding support for communicating with external equipment. If you're a developer, you can add to LinuxMCE, or even remove our modules and use LinuxMCE as a platform to do something else entirely.

LinuxMCE allows projects to work together

By allowing these various projects to work together seamlessly, many new features and benefits are now possible. For example, if there's a security breach in your house, the lights and TV's in the house come on automatically using our home automation DCE device interfaces, and the security pn pad appears on all the Windows webpads and PDA's. After 30 seconds a menacing video plays for the burglar using Xine, while the surveillance cameras monitored by Motion feed a live video to your mobile phone over GPRS. Hit 'Talk' on the phone and Xine suspends, passing control to Linphone which makes a call using Asterisk to your mobile phone with the audio piped through the stereo so you can shout at the intruder and let him know you're watching him from a remote location and calling. To the end-user, it works seamlessly, like 1 cohesive whole, but in reality, what LinuxMCE did is enable a bunch of existing applications to work together.